Utility Marking Colors: What Each Color Means

Those colored flags and paint marks across a jobsite are not random. They are part of a standardized system used to communicate what may be below the surface before excavation begins.

For utility locators, excavators, contractors, homeowners and damage-prevention professionals, understanding utility marking colors is one of the simplest ways to improve situational awareness around a dig site.

The APWA utility marking color code

The Common Ground Alliance (CGA) Best Practices guide references the APWA uniform color code for excavation sites and underground facilities. The standard color system helps crews quickly identify the general type of facility represented by a mark.

White: proposed excavation

White markings identify the proposed excavation area. Pre-marking, sometimes called white-lining, helps communicate where digging is expected to occur so the locate request can be focused on the actual work area.

Pink: temporary survey markings

Pink is used for temporary survey markings. These markings can identify survey control points, boundaries or other temporary survey information and should not be confused with a buried utility designation.

Red: electric power

Red identifies electric power lines, cables, conduit and lighting cables. Because contact with electrical infrastructure can cause severe injury, outages and property damage, red markings deserve immediate attention from anyone working in the area.

Yellow: gas, oil and other gaseous materials

Yellow marks gas, oil, steam, petroleum and other gaseous materials. These facilities can present significant safety hazards if damaged, making accurate locating and careful excavation especially important.

Orange: communications and signal systems

Orange identifies communication, alarm and signal lines, cables or conduit. This can include telecommunications and fiber infrastructure that supports homes, businesses, public safety systems and critical communications.

Blue: potable water

Blue is used for potable water facilities. Damage to water infrastructure can interrupt service, cause flooding and create costly repairs even when the facility itself does not present the same immediate hazard as electric or gas infrastructure.

Purple: reclaimed water and irrigation

Purple identifies reclaimed water, irrigation and slurry lines. These systems are distinct from potable-water facilities and are marked separately to help crews recognize what type of infrastructure may be present.

Green: sewer and drain lines

Green identifies sewer and drain lines. Damage to these systems can lead to service interruptions, environmental problems and complicated repairs.

What utility markings do—and do not—tell you

Utility markings communicate the approximate location and type of underground facilities identified during the locating process. They should not be treated as a guarantee of exact depth or as permission to excavate without following applicable safe-digging requirements.

State laws, tolerance-zone requirements and excavation practices vary. Anyone planning to dig should follow the appropriate 811 process and the requirements that apply in the state where the work is being performed.

Why the color system matters

On an active jobsite, information has to be understood quickly. A common marking language helps locators, excavators, utility owners and contractors communicate before the bucket, blade or shovel enters the ground.

That communication matters because underground infrastructure is interconnected with daily life: electricity, natural gas, drinking water, sewer systems, telecommunications and fiber all depend on facilities most people rarely see.

The professionals who identify and protect those facilities are a critical part of damage prevention. Learn more in our article Why Utility Locators Matter Before Every Dig.

Before you dig

Utility marking colors are an important visual tool, but safe excavation starts before the markings appear. Plan the work, contact 811 as required, clearly identify the excavation area, allow the required response time and use appropriate excavation practices around marked facilities.

For detailed industry guidance, see the Common Ground Alliance Best Practices guide, including its locating-and-marking guidance and uniform color-code appendix.

Built for the people behind the lines

The Safe Line USA was created to recognize the utility workers, locators, field crews and infrastructure professionals doing the work most people never see. Explore our utility worker apparel or see The Industry Tee, designed around the identity and pride of the people who protect and maintain America’s infrastructure.

The information in this article is educational and does not replace state law, local requirements, utility-owner instructions or safe-excavation procedures.